This invention relates generally to power modules for providing controlled electrical power to remote lighting fixtures and/or other loads and, more particularly, to power modules that can be slid into a rack to automatically connect to a supply of electrical power and to the loads to be controlled.
A plug-in power module of this particular kind is disclosed in U.S. Pat. No. 5,352,958 issued to David W. Cunningham et al. and entitled "Lighting Control System Dimmer Module With Plug-In Electrical Contacts." The disclosed power module includes a generally rectangular housing with one or more circuit breakers located at one end, a power device carrying one or more dimmer circuits located at an opposite end, and one or more toroidal chokes located in a middle section. The housing and the power device carry built-in electrical contacts positioned and configured to engage mating contacts in the rack when the power module is installed. One contact is for receiving electrical power, another contact is for supplying output power to the load being controlled, and a plurality of additional contacts are for receiving dimmer control signals and transmitting feedback/sensor signals. The various components of the power module are laid out efficiently within the housing, with minimal wastage of space and without the need for extraneous electrical conductors.
The power module described briefly above is highly effective in reliably controlling the delivery of electrical power to remote lighting fixtures or other loads, and it has achieved substantial commercial success. However, one deficiency of the power module is that it is not configured to detect ground faults or other causes of an imbalance in the electrical currents carried by the module's output power and return lines caused by current leakage to ground. Another deficiency is that, when a ground fault or other imbalanced condition occurs beyond a specified limit, no mechanism is provided for reporting that condition to a remote, central location.
It should, therefore, be appreciated that there is a need for an improved plug-in power module configured to sense a ground fault or other current imbalance and to trigger the module's circuit breaker, and that there further is a need for an improved plug-in power module configured to report the occurrence of such a ground fault to a remote location. The present invention satisfies these needs and provides further related advantages.